This invention relates to a method and a device for insulating parts of the spray liquid supply line, the spray liquid receptacle, feed pump etc. from the high tension voltage of an electrostatic spray gun when using an electrically conductive liquid spray material such as a water based paint or a paint containing metallic particles.
A previous method and a device for this purpose are disclosed in DE-PS 29 37 890. This prior art device comprises an open receptacle located in the spray material supply line between the spray material source and the electrostatic spray gun. A sprinkler nozzle is arranged to feed the liquid spray material into the receptacle in the form of drops which form a discontinuation of the electrical lead constituted by the spray material in the supply line between the spray gun and the spray material source. This known method and device, however, are disadvantageous in that due to the open receptacle the spray material solvent is free to evaporate into the ambient atmosphere, which causes a change in for instance the viscosity of the spray material. It also means that the spray material feed pump has to be located downstream of the insulating device, thereby being exposed to the high tension voltage led back from the spray gun via the spray material. Accordingly, in the disclosed prior art example, the feed pump drive motor is insulated from the pump by means of a long nonconductive drive shaft.
The object of the present invention is to solve the above problems of the prior art device.